As a preview, here's what Tvert said at a Littleton debate last week, as reported by the Denver Post (with a retort from a familiar face).

"We should have an honest debate," said Mason Tvert, one of the initiative's proponents, at the Littleton debate. "And honest debates begin with evidence. There just isn't any evidence of problems associated with marijuana laws as they change." ...

Ken Buck, the Weld County district attorney, said the federal government could crack down if Colorado legalized marijuana. But, even if it didn't, more liberalized marijuana laws would hurt the state's reputation.